Rengi Forge

sprite_tools_remove_bg

Cut a sprite, prop or character out of its background: exact keying for one-color backgrounds (text and holes too), AI segmentation for busy ones; clean edges with no halo, trimmed, with a pivot. AI mode handles one main subject, not text on photos. Price: $0.05 USDC via x402, charged only on success. Part of Sprite tools: 2D sprite jobs for games: cut sprites out of their background (exact for one-color backgrounds, AI for busy ones), turn animation videos into aligned sprite sheets, make normal maps for 2D lights, build 47-tile autotile sets with Tiled, Godot and Unity rules, slice a sheet into frames, pack frames into an atlas with TexturePacker and Unity metadata, and turn upscaled or AI-generated pixel art into real pixel art on its true grid with a limited palette..

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "sprite_tools_remove_bg"
  }
}

Input Schema

Name	Required	Description	Default
`keep`	No	main: only the main subject and what touches it; all: everything that is not background. auto: all for flat backgrounds, main after AI.	auto
`mode`	No	auto: flat key when the border is one color, AI segmentation otherwise.	auto
`trim`	No
`image`	No	Base64 PNG, JPEG or WebP.
`pivot`	No		bottom
`padding`	No
`imageUrl`	No

Schema Changelog

Changes observed during successful MCP inspections.

AddedOct 20, 2026

TDQS

A3.9/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full burden and does well: it discloses cost and billing behavior ('$0.05 USDC via x402, charged only on success') and output traits ('clean edges with no halo, trimmed, with a pivot'). It omits auth/setup detail beyond the price hint and any rate limits, but the payment-on-success semantics are a strong, non-obvious disclosure.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness3/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The tool-specific portion is well front-loaded and wastes little, but the trailing 'Part of Sprite tools:' catalog enumerates every sibling and bloats the description with boilerplate irrelevant to selecting this tool. Roughly half the text is generic family marketing rather than invocation guidance.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 7-parameter tool with no annotations, no output schema, and 43% schema coverage, the description covers the important behavioral surface (modes, pricing, edge quality, AI limitation). It still leaves several parameters and the return format to inference, so it is adequate but not complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is only 43%, so the description must compensate, and it partially does by explaining keying behavior ('text and holes too') and the AI single-subject limit, which governs the 'mode'/'keep' choices. However, parameters like 'padding', 'imageUrl', and the 'trim'/'pivot' defaults get only passing mention ('trimmed, with a pivot'), leaving gaps the low schema coverage does not fill.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Cut a sprite, prop or character out of its background') and immediately disambiguates the two operating modes (exact keying for one-color backgrounds vs AI segmentation for busy ones). An agent can distinguish this from siblings like sprite_tools_slice or sprite_tools_pack without opening the schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives clear context for mode selection ('exact keying for one-color backgrounds, AI segmentation for busy ones') and an explicit when-not caveat ('AI mode handles one main subject, not text on photos'). It does not route the agent away from sibling tools, but the internal guidance is strong and actionable.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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